docs: def nack(self, channel_id=None, **kwargs):  # pragma: no cover
          """Send a negative read-acknowledgement to the service.
  
          Causes the channel's read point to move to its previous position
          prior to the last poll.
  
          Args:
              channel_id (str): The channel ID.
              **kwargs: Supported :meth:`~pancloud.httpclient.HTTPClient.request` parameters.
  
          Returns:
              requests.Response: Requests Response() object.
  
          Examples:
              Refer to ``event_nack.py`` example.
  
          """
          path = "/event-service/v1/channels/{}/nack".format(channel_id)
          r = self._httpclient.request(
              method="POST",
              url=self.url,
              path=path,
              **kwargs
          )
          return r